The use of monoclonal antibodies (MABs) in diagnostic and therapeutics applications is on the rise; yet there are limitations to the current hybridoma technology. There is a need to develop less expensive, novel and improved technologies for MAb production. The application of recombinant technology has made it possible to generate single chain, chimeric and humanized MAbs with desired specificity. The goal of this SBIR Phase I proposal is to demonstrate utility of an efficient yeast expression system for production of a recombinant prototype MAbs. This will be achieved by construction of separate expression cassettes for the antibody H and L chains with a galactose regulated hybrid promoter, a leader sequence, and cDNAs for H or L chains. Both cassettes will be cloned into high copy yeast vector at two different cloning sites. This twin cassette plasmid will be transformed into yeast strains, the recombinant proteins produced will be confirmed by Western blot analysis. Thus at the end of Phase I, we would have proof of concept for the production of an improved system for Mabs using a reliable and inexpensive procedure. Phase II will include production of several MAbs of biomedical applications using this model yeast expression system. PROPOSED COMMERCIAL APPLICATIONS: Total Mabs revenues were $1 billion in 1992 and are expected to increase to $6 billion by year 2000. In Phase I we plan to test the feasibility of an efficient yeast system which can reduce the cost and time for producing MAbs for biomedical applications. The total market for Mabs based diagnostic tests alone were $300 mi in 1992 and market for home based diagnostic tests like these will grow as it helps reduce the cost of medical expenses and reduce the cost of health care.